Lack of sleep affects immune response

Sleep experts say that lack of sleep can be as damaging to the immune system as physical stress.

A research team from Erasmus University in the Netherlands and the University of Surrey, UK, said that both sleep deprivation and physical stress jolt the immune system into action.

Writing in the journal Sleep, the scientists said sleep deprivation in healthy young men had an impact on granulocytes, a type of white blood cell, which were produced in hugely inflated numbers among study subjects deprived of normal sleep.

The study focused on 15 healthy adult males who were tested while they were sleeping eight hours a night for a week, and again after they had been deprived of sleep.

During the study, the subjects were told to stay off alcohol or caffeine, and were exposed to more than 15 minutes of outdoor light within 90 minutes of waking, with the aim of stabilising their circadian rhythms.

The researchers then compared the men's white blood-cell counts during their normal sleep/wake cycle week to the count during the second part of the experiment.

For this part of the study, the subjects were kept awake for 29 hours straight.

The researchers found that the production of granulocytes responded immediately to sleep deprivation, and that it rose particularly sharply at night.

Granulocytes get their name from the microscopic enzyme sacs they hold, which are used to digest microorganisms. They are categorised by scientists according to how they react to staining processes in a laboratory: they include eosinophils, basophils and neutrophils.

They have a broad-based action on a wide variety of microorganisms, and are an innate part of our immune response.

By contrast, B-cells and T-cells only respond to specific antigens.

According to study lead author Katrin Ackermann, further research would be needed to reveal the molecular mechanisms behind the immediate stress response, and to clarify its role.

Certain diseases, including high blood pressure, or hypertension, type 2 diabetes and obesity, have been linked to chronic sleep deprivation.

Ackermann said her team's study, once confirmed with a larger study, would have profound implications for doctors, as well as for industries which routinely require rotating shift work from employees.

Long-term sleep loss is a major risk factor for immunological problems, and previous research has established the immune system is kept in tune by regular sleep patterns.